The invention relates to a seat belt control device for controlling retraction of a seat belt through a motor in a seat belt system having the motor for retracting the seat belt.
In a seat belt to be used in a vehicle or automobile, a tension is provided by a seat belt retractor. In other words, in case the seat belt is used, one portion of the seat belt wound by a spring in the seat belt retractor is pulled out by a passenger and engaged with a part of the seat belt fixed to a seat through a buckle. Thereafter, when the passenger leaves the hands from the seat belt, the loosened seat belt is wound up by an action of the spring in the seat belt retractor and a tension determined by the spring is provided to the seat belt to thereby bind or hold the passenger to the seat.
However, in such a spring-type retracting mechanism, when a spring force for retracing the seat belt is made weak, the seat belt is not sufficiently retracted to remain looseness. On the contrary, when the spring force is made strong, the passenger wearing the seat belt receives a pressed or tightened feeling.
To solve the above problems, the present inventors have proposed a seat belt driving device for easily loosening a binding force of a seat belt by pulling thereof, which can cooperate with a retracting control flexibly, as disclosed in Japanese Patent Application No. 11-126242 (hereinafter referred to as xe2x80x9cprecedent patent applicationxe2x80x9d). In the preceding patent application, a direct current (hereinafter referred to as xe2x80x9cDCxe2x80x9d) motor is used to drive the seat belt, and a pulse width modulation (hereinafter referred to as xe2x80x9cPWMxe2x80x9d) control or a pulse width constant.period variable control is carried out to control a rotating direction and a rotating speed of the DC motor.
However, in the precedent patent application, a retraction of the seat belt through a motor is carried out only when disengagement of a buckle and a tongue plate is detected by a buckle switch disposed in the buckle, and only for a predetermined time.
Therefore, for example, in case a passenger holds the seat belt with hands while the retraction is being carried out, the seat belt remains loose. Thus, there have been problems such that the seat belt is caught by a projection in a compartment or caught by the door.
In view of the above problems, the present invention has been made, and an object of the invention is to provide a seat belt control device, by which a seat belt is positively retracted so that the seat belt is not caught by a projection in a compartment of an automobile nor caught by a door when a passenger gets off or is going to get off.
Further objects and advantages of the invention will be apparent from the following description of the invention.
According to a first aspect of the invention to attain the above object, a seat belt control device for controlling retraction of a seat belt through a motor includes a passenger detector in an automobile compartment, wherein when the passenger detector detects that no passenger is present in an automobile or when such a condition is held for a predetermined time, the seat belt is retracted.
In the first aspect, when the passenger gets off or when such a condition is held for a predetermined time, the seat belt is retracted. For example, even if the seat belt remains loose when disengagement of a buckle and a tongue plate is made, thereafter, the seat belt can be securely retracted to thereby prevent the seat belt from being caught by a projection in a compartment or a door of the automobile. As the passenger detector, for example, a known detector employing infrared rays used for an automatic door or the like may be employed.
According to a second aspect of the invention to attain the above object, a seat belt control device for controlling retraction of a seat belt through a motor includes a door switch, wherein when the door switch detects that a door is open or when such a condition is held for a predetermined time, the seat belt is retracted.
In the second aspect, when the door is open or such a condition is held for a predetermined time, the seat belt is retracted based on the judgement that the passenger is going out or, at least, the passenger is not wearing the seat belt. Thus, even if the seat belt remains loose without being retracted when the tongue plate is disengaged from the buckle, thereafter, the seat belt can be securely retracted to thereby prevent the seat belt from being caught by a projection in the compartment or the door of the automobile.
According to a third aspect of the invention to attain the above object, a seat belt control device for controlling retraction of a seat belt through a motor includes an engine key switch, wherein when the engine key switch detects that an engine key is pulled out, an engine is turned off, or such a condition is held for a predetermined time, the seat belt is retracted.
In the third aspect, when it is detected that the engine key is pulled out or the engine is turned off, or when such a condition is held for a predetermined time, the seat belt is retracted based on the judgement that the passenger gets off or, at least, the passenger does not wear the seat belt. Thus, even if the seat belt remains loose when the tongue plate is disengaged from the buckle, thereafter, the seat belt can be positively retracted to thereby prevent the seat belt from being caught by a projection in the compartment or by a door of an automobile.
According to a fourth aspect of the invention to attain the above object, in any of the first to third aspects, a retracting time of a seat belt is a predetermined time.
In the fourth aspect, since retraction of the seat belt is terminated after passage of a predetermined time from a start of the retraction, a load is not applied to the motor for a long time and an electric current of a battery is not uselessly consumed. It is preferable to set the predetermined time to a sufficient time required for retracting the seat belt.